Thursday, December 22, 2011

Vagabonding across the 39th Parallel: A Magical Evening in the Mesozoic

Ah, winter solstice! The longest nights, the shortest days, and although we don't get snow and hyperfreezing temperatures, there are mornings when I consider putting on a jacket before going for the newspaper. Yup, living in California can be tough. I admit, though, to really hating our tule fogs that occur this time of year. So what to do? Obviously, I need to go back and finish up my vagabonding series. We were exploring the geology of a swath of land between California and Colorado that happened to lie close to the 39th parallel last July. We were drifting along, not rushing, not planning more than a day or two in advance, and we were now on the homeward road. We had spent the morning and early afternoon exploring Arches National Park, and looking at petroglyphs, pictographs and dinosaur footprints, but now we had a bit of a distance to go, hoping to find a place to stay at Capitol Reef National Park.

Capitol Reef? In the desert? Being a geological blog, one might think that 'reef' refers to an ancient coral reef preserved in a limestone layer somewhere, but that is not the case here. Settlers in the region referred to cliffs and ridges that were barriers to travel as reefs. That was certainly the case here: Capitol Reef National Park preserves much of the Waterpocket Fold, a monocline fold that runs for more than 100 miles in a north-south direction. The fold defies travel; few of the canyons that cut across the fold are wide enough for trails, much less highways. The first paved highway wasn't constructed until 1962.

A monocline isn't like other folds. Anticlines are flexed upwards, while synclines are flexed downwards. Monoclines are neither; the sedimentary layers in a monocline can be thought of as a rug draped over a step. The layers are horizontal on both sides of the fold, but higher on one side. These features are most often caused when faults at great depth lift the overlying rocks, but without fracturing the softer sedimentary layers. A number of monoclines cross the Colorado Plateau; one forms the eastern edge of the Grand Canyon. But few monoclines are as dramatic as the Waterpocket Fold at Capitol Reef.

Erosion has cut deep into the fold, exposing thousands of feet of colorful sediments deposited during the Mesozoic era, the age of the dinosaurs. The layers tell a story of the giant supercontinent Pangea. In this part of the world, conditions changed from river floodplains to desert dune fields to rivers, to dunes again, and then the region was inundated by shallow seas several times. The story is readily discerned by carefully observing the rocks while exploring Highway 24 running east-west across the park. On the west side, the cliff-forming Wingate Sandstone protects the underlying soft layers from erosion, forming a tall escarpment that is nicely situated to capture the rays of the setting sun.

We arrived very late in the afternoon, just in time to see the setting sun lighting the cliffs. The roads were empty as people were settling in for the night. We weren't quite ready to turn in, so we headed south on the park's Scenic Road. I had told Mrs. Geotripper that the road was nicely paved, but when we arrived, we found that all the asphalt was torn out for construction. It was a bit bumpy and dusty, but I realized we were kind of reliving what it was like to explore the region half a century ago.

Capitol Gorge was the route of the old "highway" through the reef. In the narrows there is barely room for a car to squeeze through, and the watercourse was always subject to flooding and closure. In the daytime, one can walk through the gorge and see Fremont petroglyphs and pictographs, as well as more recent inscriptions from travelers in the late 1800s and early 1900s.

This evening, it was dark and lonely and I found myself imagining what it was like to travel this road decades ago, or centuries ago. Even today the population of the region is only a few thousand people scattered over thousands of square miles. A mistake, an accident, a flood, and one could be in real trouble. It is a harsh land, and it was a hard life for those who lived here: the Fremont and other Native Americans, the Mormon pioneers who settled nearby in Fruita, and those who make a life there now.

It was dark. We slowly made our way out the gorge and headed back to camp. The next day we would drive one of the most spectacular roads that no one knows about...

About Me

I am a teacher of geology at Modesto Junior College and former president of the National Association of Geoscience Teachers, Far Western Section. I have led field trips all over the western United States, and a few excursions overseas, but my homebase is the Sierra Nevada, the Great Valley, and the Coast Ranges of California.

Ask Geotripper

Is there something about geology that you are curious about? Do you have questions about the scientific aspects of political controversies? I can try to provide a scientist's perspective. Your questions and possible answers could be a springboard to a blog discussion, or they can be private. Anonymity is always assumed. Contact Geotripper at hayesg (at) mjc.edu.

Blooks, Boogers and Bleries

Here are some of the series I've produced for the Geotripper Blog:

The Other California: what to see when you've seen all the really famous places in the Golden State (in progress).Into the Great Unknown: A rafting journey down the Colorado River through the Grand Canyon. The most incredible adventure of my life (so far)!

The Hawai'i That Was: An exploration of the geology, natural history, and anthropology of the most isolated lands on the planet. It's a lot more than beaches, shopping, and palm trees!